Role of multi detector computed tomography in the evaluation of retroperitoneal masses

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*Corresponding author:Gurumurthy B

ISSN: 0976-3031

Research Article

ROLE OF MULTI DETECTOR COMPUTED TOMOGRAPHY IN THE EVALUATION OF

RETROPERITONEAL MASSES

**Gurumurthy B*., Kiran Kumar Hegde., Jeevika M U., Pooja Subramanya.,**

Guruprasad C., Vikas M and Punya J

Department of Radiodiagnosis, JJM Medical College, Davangere, Karnataka

DOI: http://dx.doi.org/10.24327/ijrsr.2018.0911.2881

ARTICLE INFO ABSTRACT

Retroperitoneal masses are one of the diagnostic challenges. Multidetector computed tomography (MDCT) is considered as ideal imaging modality in evaluating the retroperitoneal masses. The objective of this study was to locate, differentiate and diagnose the retroperitoneal masses. It is a prospective study where72 patients were evaluated at JJMMC, Davangere over a period of 2 years from October 2016 to October 2018.Out of the 72 cases of retroperitoneal masses, 23 cases (32%) were primary retroperitoneal mass lesions. Further, out of the 49 cases (68%) of masses arising from retroperitoneal organs, 19% were of pancreatic origin, 17 % of renal origin, 12 % adrenal origin and 2% of aortic origin. The present study concludes that using MDCT it is possible to localise, differentiate and diagnose the retroperitoneal masses. Based on characteristic features and relevant clinical information narrowing of differential diagnosis is possible.

INTRODUCTION

The retroperitoneum is a fat containing compartment extending from the diaphragm superiorly to the pelvis inferiorly and is situated between the posterior parietal peritoneum anteriorly and the transversalis fascia posteriorly.1 In addition to fat, it contains true embryonic organs being adrenal gland, kidneys, ureters and gonads. Many other abdominal viscera are not completely within the retroperitoneum but closely associated with the posterior abdominal wall being partly covered by the peritoneum. These structures include the aorta, inferior vena cava and their branches, pancreas, portions of the duodenum and colon, and many lymph nodes and nerves.2

Retroperitoneal masses are one of the diagnostic challenges which include precise localization, determination of extent of involvement and characterization of specific pathologic type.3 To most clinicians and radiologists, the retroperitoneum was merely a diffuse vague space located between the posterior peritoneum and posterior abdominal wall.4 Today, with detailed visualization of this area by CT scanning, the anatomy and fascial boundaries can be explained and visualised better.4 Ultrasonography plays a relatively limited role in evaluation of retroperitoneal masses except for the assessment of vascular

invasion which could be performed better with CT and MRI imaging.1

Multidetector computed tomography (MDCT) is considered as ideal imaging modality in evaluating the retroperitoneal masses since it provides discrete cross sectional images of organs and retroperitoneal compartments.5

Familiarity with MDCT and clinical features of various retroperitoneal lesions facilitates accurate diagnosis and in obtaining clinically significant information which in turn helps in their management.3

Objective of the Study

 To locate, differentiate and diagnose the retroperitoneal masses.

 To evaluate the nature, morphology and extent of the mass and its relationship to adjacent structures.

 To compare the CT finding with the surgical and histopathological findings wherever possible.

International Journal of

Recent Scientific

Research

International Journal of Recent Scientific Research

Vol. 9, Issue, 11(B), pp. 29557-29562, November, 2018

Copyright © Gurumurthy B et al, 2018, this is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.

DOI: 10.24327/IJRSR

CODEN: IJRSFP (USA)

Article History:

Received 6th August, 2018 Received in revised form 15th September, 2018

Accepted 12th October, 2018

Published online 28th November, 2018

Key Words:

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Gurumurthy B et al., Role of Multi Detector Computed Tomography In The Evaluation of Retroperitoneal Masses

MATERIALS AND METHOD

Source and method of collection

It is a prospective study conducted on 72 cases at JJMMC, Davangere over a period of 2 years from October 2016 to October 2018. All the patients were subjected to MDCT on TOSHIBA Activion 16 slice MDCT machine.

contrast dual phase study of the abdomen and pelvis will be done. Bowel opacification will be achieved orally with 1000ml of diluted contrast for differentiating fluid filled bowel loops. It consists of acquisition of contiguous axial secti

thickness 5mm of abdomen and pelvis in cranio direction from the level of the xiphisternum to pubis symphysis before and after administration of iodinated intravenous contrast. IV contrast opacification is achieved with 100 of non ionic contrast media (0.9ml/kg body weight) by infusing at the rate of 3ml/sec. Dual phase study will be done with arterial phase at 20-40sec and venous phase at 70

window width for soft tissue is 350-400HU and for bone is 1500-2000HU. The window level for soft tissue is 50HU and for bone is 450HU. MDCT Findings were correlated with the surgical and HPE findings wherever applicable.

Inclusion Criteria

 Patients of all age groups and gender with clinical suspicion presenting with symptoms of involve

retroperitoneal structures

 Patients of all age groups and gender with involvement of retroperitoneal organs detected incidentally by routine ultrasonography of abdomen.

Exclusion Criteria

The study will exclude

 Patients presenting with non-retroperitoneal lesions excluded by initial/routine ultrasonographic screening

 Patients with altered renal parameters are excluded from the study as intravenous contrast agent cannot be administered in such patients.

 Patients with sensitivity to contrast agent reactions).

 Patients in whom a CT examination is contraindicated (Example: Pregnancy).

Statistical analysis

Statistical analysis was performed using percentages and proportions.

RESULTS

Table 1 Age and Sex Distribution

Age Range Number of

Males

Number of Females

0-1 1 0

2-10 1 1

11-20 1 1

21-30 4 1

31-40 11 7

41-50 5 4

51-60 10 6

61-70 15 4

Total 48 24

Role of Multi Detector Computed Tomography In The Evaluation of Retroperitoneal Masses

It is a prospective study conducted on 72 cases at JJMMC, Davangere over a period of 2 years from October 2016 to October 2018. All the patients were subjected to MDCT on TOSHIBA Activion 16 slice MDCT machine. Plain and post-contrast dual phase study of the abdomen and pelvis will be done. Bowel opacification will be achieved orally with 1000ml of diluted contrast for differentiating fluid filled bowel loops. It consists of acquisition of contiguous axial sections, of thickness 5mm of abdomen and pelvis in cranio-caudal direction from the level of the xiphisternum to pubis symphysis before and after administration of iodinated intravenous contrast. IV contrast opacification is achieved with 100-120ml c contrast media (0.9ml/kg body weight) by infusing at the rate of 3ml/sec. Dual phase study will be done with 40sec and venous phase at 70-90ses. The 400HU and for bone is evel for soft tissue is 50HU and for bone is 450HU. MDCT Findings were correlated with the surgical and HPE findings wherever applicable.

Patients of all age groups and gender with clinical suspicion presenting with symptoms of involvement of Patients of all age groups and gender with involvement of retroperitoneal organs detected incidentally by routine

operitoneal lesions excluded by initial/routine ultrasonographic screening Patients with altered renal parameters are excluded from the study as intravenous contrast agent cannot be Patients with sensitivity to contrast agent (Allergic Patients in whom a CT examination is contraindicated

Statistical analysis was performed using percentages and

Age and Sex Distribution

Number of Total 1 2 2 5 18 9 16 19 72

Graph 1 Age and Sex Distribution

Table 2 Primary retroperitoneal masses vs masses arising from retroperitoneal organs/secondary retroperitoneal masses

Primary retroperitoneal

masses

retroperitoneal

23

Graph 2 Primary retroperitoneal masses vs masses arising from retroperitoneal

organs/secondary retroperitoneal

Graph 3 Primary Retroperitoneal masses spectrum

Table 3 Primary Retroperitoneal mass spectrum

Primary Retroperitoneal mass Lymphoma Liposarcoma Leiyomyosarcoma Schwannoma Neurofibroma Paraganglioma Teratoma Abscess Hematoma 0 2 4 6 8 10 12 14 16

0-1 2-10 11-20 21-30

32%

68%

0% 0% Number of cases

Age and Sex Distribution

Primary retroperitoneal masses vs masses arising from econdary retroperitoneal masses

Secondary retroperitoneal

masses

Total

49 72

Primary retroperitoneal masses vs masses arising from retroperitoneal organs/secondary retroperitoneal masses

Primary Retroperitoneal masses spectrum

Primary Retroperitoneal mass spectrum

Retroperitoneal mass Number of cases

10 5 1 2 1 1 1 1 1

30 31-40 41-50 51-60 61-70

Males

Females

Number of cases

Primary Retroperitoneal masses

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Total 23

Table 4 Primary Retroperitoneal mass: neopl neoplastic lesions

Neoplastic lesions

Non- neoplastic lesions

21 2

Graph 4 Primary Retroperitoneal mass: neoplastic vs non

Table 5 Secondary retroperitoneal masses

Organ of origin of retroperitoneal

masses

Number of cases

Adrenal 12

Renal 17

Pancreatic 19

Aorta 1

Total 49

Graph 5 Secondary retroperitoneal masses - organ of origin

Table 6 Secondary retroperitoneal masses: neoplastic vs non neoplastic lesions

Neoplastic lesions Non-neoplastic lesions

34 15

Neoplastic lesions Non-neoplastic lesions 0 5 10 15 20 25 24% 35% 39% 2%

Number of cases

0 5 10 15 20 25 30 35 40 Neoplastic lesions Non-neoplastic lesions

Number of cases

Neoplastic lesions

Non

Primary Retroperitoneal mass: neoplastic vs

non-Total

23

Primary Retroperitoneal mass: neoplastic vs non-neoplastic lesions

toneal masses - organ of origin

Number of cases

organ of origin

retroperitoneal masses: neoplastic vs

non-Total

49

Graph 6 Secondary retroperitoneal masses: neoplastic vs non

lesions

Fig 1 Secondary retroperitoneal masses spectrum

Table 7 Cystic Retroperitoneal masses

Cystic Retroperitoneal masses

Cystic schwannoma Neurofibroma

Teratoma Pancreatic pseudocyst Serous cystadeenoma pancreas Mucinous cystadenoma pancreas

Renal abscess Adrenal hematoma Psoas abscess Urinoma Psoas Hematoma Total

Graph 7 Cystic Retroperitoneal masses

Table 8 Fat containing retroperitoneal masses

Fat containing retroperitoneal masses Liposarcoma Teratoma Renal angiomyolipoma Adrenal adenoma Adrenal myelolipoma Total Neoplastic lesions Non- neoplastic lesions Adrenal Renal Pancreatic Aorta Neoplastic lesions Non-neoplastic lesions Adrenal origin

• Adenoma (4) • Metastasis (2) • Carcinoma (1) • Hematoma (2) • Neuroblastoma

(2) • Myelolipoma (1)

Renal origin

• Renal Cell Carcinima (7) • Oncocytoma (2) • Wilms Tumor (2) • Angiomyolipoma

(4) • Abscess (1) • Urinoma (1)

0 2 4 6 8 10

12 _{Number of cases}

Secondary retroperitoneal masses: neoplastic vs non-neoplastic lesions

Secondary retroperitoneal masses spectrum

Cystic Retroperitoneal masses

Cystic Retroperitoneal masses Number of cases

1 1 1 10 Serous cystadeenoma pancreas 2 Mucinous cystadenoma pancreas 2 1 2 1 1 1 23

Cystic Retroperitoneal masses

Fat containing retroperitoneal masses

Fat containing

retroperitoneal Numbers

of lesions

Liposarcoma 5

Teratoma 1

angiomyolipoma 4 Adrenal adenoma 3 Adrenal myelolipoma 1 14

Angiomyolipoma

Pancreatic Origin

• Pseudocyst (10) • Adenocarcinoma (5) • Serous Cystadenoma (2) • Mucinoius Cystadenoma (2) Aortic Origin

• Aortic Aneurysm (1)

Number of cases

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Graph 8 Fat containing retroperitoneal masses

Cases

Case 1 Benign cystic teratoma

Findings: NECT axial images showing large lobulated

retroperitoneal cystic lesion with thin internal septations, fat component and few calcific foci.

0 1 2 3 4 5

6 Numbers of lesions

taining retroperitoneal masses

NECT axial images showing large lobulated retroperitoneal cystic lesion with thin internal septations, fat

Case 2 Leiyomyosarcoma

Findings: CECT axial and sagittal images retroperitoneal

lesion showing central extensive necrosis and heterogeneous enhancement. The lesion showed involvement of adjacent IVC with loss of fat plane between them and associated IVC thrombus.

Case 3 Neuroblastoma

Findings: CECT axial imagesshowing well defined

heterogeneously enhancing retroperitoneal mass with few areas of calcification and necrosis. Lesion is encasing the IVC all around the circumference and bilateral renal vessels.

Numbers of lesions

Leiyomyosarcoma

CECT axial and sagittal images retroperitoneal lesion showing central extensive necrosis and heterogeneous enhancement. The lesion showed involvement of adjacent IVC with loss of fat plane between them and associated IVC

Neuroblastoma

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Case 4 Paraganglioma

Findings: CECT axial images showing large well defined

lobulated heterogeneous retroperitoneal mass with haemorrhagic areas.

DISCUSSION

Symptoms due to retroperitoneal tumours are vague and non-specific and present late in course of disease by compression of organs and obstructive phenomena.6 Diagnosis is made by radiological methods and after histopathological examination and surgery. Diagnosis is often challenging for radiologists.3Thus retroperitoneal pathologies are a unique category in diagnostic radiology and need a logical stepwise, feasible approach for diagnosis.

The first step is to characterisetumour location and organ of origin and look for specific features of various retroperitoneal tumours.3 CT is an easily performed, rapid and safe, diagnostic imaging modality and is highly accurate in determining the organ of origin, characterization and extent of the mass.7 This was a prospective study in the Department of Radiodiagnosis, JJMMC, Davangere aimed at studying the role of MDCT in evaluation of retroperitoneal masses.

Pathologies

Out of the 72 patients who were evaluated, 23 cases (32%) were found to be primary retroperitoneal masses. The rest 49 cases (68%) were masses arising from retroperitoneal organs.

Primary retroperitoneal masses: Among the 23 cases of

primary retroperitoneal mass lesions, 21 were found to be neoplastic and 2 were non-neoplastic lesions. Rest of the lesions weretumours of neurogenic origin, teratoma, psoas abscess and hematoma.

Lymphoma: Lymphomas accounted for 43.5% and formed the

majority among the primary retroperitoneal mass lesions which was consistent with findings of the study by Chaudhariet al.8 Rajiah et al described lymphomas at CT as well defined homogenous masses with mild homogeneous enhancement spreading between normal structures without compressing them. The study also described the anterior displacement of aorta and IVC producing the classical floating aorta/ CT angiogram sign. It is also stated that calcifications and necrosis are unusual before therapy. 1

In our study, we found that out of the 10 cases of lymphomas, 6 had well defined lobulated margins, and majority of 8 of them showed the classical floating aorta sign and vascular encasement. On post contrast study, 6 showed mild homogeneous enhancement and rest showed heterogeneous. Only 2 cases showed necrosis.

Mesodermal tumors:In our study, the 2nd largest group was

mesodermal neoplasm forming 26% (6 cases) with liposarcoma being the most common. This is consistent with the study by Rajiah et al. Liposarcoma showed thick, irregular, and nodular septa. On post contrast study, they showed enhancement. These features help in differentiating it from lipoma as described above.1

The study included a case of leiomyosarcoma which was ill defined heterogeneous mass with extensive area of necrosis and extending into the surrounding vasculature and associated IVC thrombosis. This finding is consistent with that found in the article by Rajiah et al. Which describes leiomyosarcoma to arise from combination of extravascular and intravascular components. The extensive area of necrosis with adjacent vascular involvement found in the lesion points towards the diagnosis of leiomyosarcoma.1

Neurogenic tumors: Four cases in the study diagnosed as

primary retroperitoneal masses on CT were confirmed to be neurogenic tumors on histopathological examination. Among them two cases were of schwannoma, one each of neurofibroma and paraganglioma.

The mass diagnosed as schwannoma appeared as a well defined homogenous mass in the paravertebral region with heterogeneous enhancement on post contrast study.

Paraganglioma was seen as a large well-defined lobulated mass with haemorrhage and intense enhancement on post contrast study suggesting hypervascularity of the tumor, the finding of which is consistent with the description by Rajiah et al. 1

Germ cell tumor: The retroperitoneal teratoma in this study

appeared as a complex mass that contained multiple well-circumscribed fluid components, fat, and calcification in a tooth like configuration. This was consistent with the characteristic imaging features of teratoma as described by Shin et al.9 The non -neoplastic primary retroperitoneal masses included psoas abscess and hematoma.

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In our study, the retroperitoneal masses were of pancreatic, adrenal, renal and aortic origin.

Out of the 19 masses of pancreatic origin, 10 were of pseudocysts, 5 were of adenocarcinoma, 2 each of serous and mucinous cystadenomas. Pancreatic pseudocysts showed variable presentations with two of them showing splenic and portal vein thrombosis. And one case being associated with pancreatico-pleural fistula.

Renal lesions consisted 7 cases of RCC, 2 cases of oncocytoma, 2 cases of Wilms tumour and 2 cases of angiomyolipoma. Out of the 7 cases of RCC that were included in the study, 5 showed embedded organ sign, one showed beak sign, and the other showed both embedded organ & beak sign. 2 cases had distant metastasis. One of the two cases of renal tumors diagnosed on HPE showed central stellate scar.

Adrenal lesions consisted of 4 cases of adenoma, 2 of metastasis, 1 of carcinoma, 2 of neuroblastoma and 1 of myelolipoma. Of the four adrenal adenomas, 3 showed HU value of less than 10. While one lesion of HU value of around 20 showed washout of >60% on delayed study, findings consistent with the findings of adrenal adenoma. All the adrenal adenomas showed phantom sign. Both the adrenal metastatic lesions were found to be from primary lung malignancy.

Both the cases of neuroblastoma included in the study were seen in paediatric age group. On CT, both were seen as heterogeneous masses with calcifications. One of which showed embedded organ sign while the other showed floating aorta sign in addition to it along with distant metastasis. The case of adrenal myelolioma in the study was a heterogeneous mass with areas of fat and enhancing soft tissue, consistent with description of adrenal myelolipomas by Rajiahet al.1

CONCLUSION

To most clinicians and radiologists, the retroperitoneum was merely a diffuse vague space located between the posterior peritoneum and posterior abdominal wall, which gets affected by few pathologies.1 Symptoms due to retroperitoneal pathologies are vague and non-specific and present late in course of disease by compression of organs and obstructive phenomena.6 Today with detailed visualization of this area by CT scanning , the anatomy and facial boundaries can be explained and visualised better.1

Thus, the diagnosis of this unique category in diagnostic radiology has become feasible with logical stepwise approach using MDCT. The first step being identification of the mass as a retroperitoneal mass and the organ of origin based on specific imaging signs. Next steps being the identification of specific patterns of spread and characteristic tumour components

The present study concludes that using MDCT it is possible to localise, differentiate and diagnose the retroperitoneal masses. It is also possible to evaluate the nature, morphology and extent of the mass and its relationship to adjacent structures.

However, assigning a specific diagnosis for every mass lesion might be difficult, considering the overlapping imaging features, but based on characteristic features and relevant clinical information narrowing of differential diagnosis is possible.

In addition to diagnosing the pathologies, MDCT helps in staging and guided biopsies of the retroperitoneal masses. CT also helps in assessment after radiotherapy or chemotherapy treatment.

Reference

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3. Nishino M, Hayakawa K, Minami M, Yamamoto A, Ueda H, Takasu K. Primary Retroperitoneal Neoplasms: CT and MRI Imaging Findings with Anatomic and Pathologic Diagnostic Clues. Radiographics. 2003; 23:45-57.

4. GothlinI. Computed Tomography of the Retroperitoneum: An Anatomical and Pathological Atlas with Emphasis on the Fascial Planes. Radiology 1985; 154(2): 468.

5. Yang DM, Jung DH, Kim H, Kang JH, Kim SH, Kim JH, et al. Retroperitoneal Cystic Masses: CT, Clinical and Pathologic Findings and Literature Review. Radiographics. 2004; 24:1353-65.

6. Venter A. Difficulties of diagnosis in retroperitoneal tumors. Rom J Morphol Embryol. 2013; 54(2):451-6. 7. Fusari M, Maurea S, Imbriaco M. Comparison between

multi slice CT and MR imaging in the diagnostic evaluation of patients with pancreatic masses. Radiol Med (Torino). 2010; 115(3):453-66.

8. Chaudhari A, Desai PD, Vadel MK, Kaptan K. Evaluation of primary retroperitoneal masses by computed tomography scan. Int J Med Sci Public Health. 2016;5(7):1423-9.

9. Shin N, Kim M-J, Chung J-J, Chung Y-E, Choi J-Y, Park Y-N. The Differential Imaging Features of Fat-Containing Tumors in the Peritoneal Cavity and Retroperitoneum: the Radiologic-Pathologic Correlation. Korean J Radiol. 2010; 11(3):333-45.

How to cite this article:

Gurumurthy B et al.2018, Role of Multi Detector Computed Tomography In The Evaluation of Retroperitoneal Masses. Int J Recent Sci Res. 9(11), pp.29557-29562. DOI: http://dx.doi.org/10.24327/ijrsr.2018.0911.2881